This insistence on starting Smart at PG is causing these small backcourt problems. You can't start Smart and play two 6-1 PGs off the bench substantial minutes (Schroder, Pritchard) and avoid those bad backcourts.
Smart has to start at SG with Jaylen at SF and Tatum at PF in order to bring balance to this team's rotation. Then Schroder and Pritchard can share the PG duties. Rob Williams and Horford can share the C minutes and maybe some minutes alongside each other. Romeo, Nesmith and J.Richardson can jockey for the backup SG & SF minutes.
Then the PF minutes can go in a few different directions depending on what Udoka wants. He can go Grant Williams. He can go Juancho. He can play more minutes Horford & Rob Williams together. He can go smaller with Jaylen backing up Tatum with two wings next to him and one small PG on the court.
But it all starts with how Marcus Smart is used.
Or ... bench Pritchard or Schroder. Play only one of them and glue the other to the bench. You cannot play both if Smart is your starting PG.